A blog by Catharine Ellis

Month: September 2016

Eucalyptus is not native to where I live but I have watched dyers (with a bit of envy) from other parts of the world use these plants as a source of color and tannin. Each year I grow a plant or two for experimentation. These experiments have led me to some interesting observations.

The variety commonly found at our local garden center is Silver Dollar Gum (Eucalyptus cinerea). A friend, visiting from Australia, fondly recognized it in the garden as “gummy”. It will grow as an annual here and I always dry the round “silver dollar” leaves for dye. Sometimes I can even acquire them amongst the floral arrangements in the local grocery store. This year I had a additional variety (Eucalyptus globulus). It was grown by a friend from seeds that she brought from a tree in her yard in Ethiopia.

Silver dollar gum (Eucalyptus cinerea)

Eucalyptus globulus,

Dye tests were done on wool, both with and without an alum mordant, using dried leaves at 100% of the weight of fiber. Plants contain many different colorants. In the case of the Eucalyptus leaves, they contain both a flavonol and a tannin. The flavonols are typically yellow in color and require a mordant to attach to the fiber. The tannins produce a variety of colors and do not require a mordant.

I placed non-mordanted wool fabric in the bath with the leaves. It was brought to a low simmer (approximately 190 degrees F). The color was slow to come but after about 2 hours the Eucalyptus cinerea resulted in a deep red/orange, while the Eucalyptus globulus turned a deep brown.

Alum-mordanted wool was dyed in a separate bath. The fiber quickly (within 30 minutes) turned a brilliant yellow from both varieties of eucalyptus. I removed some of the fiber from the dyebath when the yellow was still bright. As the rest of the fiber stayed in the bath, the tannins were released, changing the color of the wool from yellow to either a deep yellow/orange or a yellow brown. After two hours in the bath the mordanted fiber had been dyed by BOTH the flavonol and the tannin.

Several years ago I heard Michel Garcia say that the clearest yellow color from plants may come at the beginning of a dyebath, before any tannins are extracted. As the fiber stays in the bath with the dyestuff, the tannins are released and the color becomes deeper and duller. The eucalyptus is a dramatic illustration of this principle but other plant materials also indicate the same principle.

Alum mordanted linen fabrics were dyed with small, leafed branches of dyer’s broom (Genista tinctoria). Time in the bath ranged from 15 minutes to 2 hours. The most brilliant yellow was achieved after 30 minutes. After that time the color got deeper and duller, most likely from the tannins released.Henna, (Lawsonia intermis) which contains flavonols (mainly luteolin), naphthaquinone (lawsone) and tannins: (left to right) mordanted wool 30 minutes in bath, mordanted wool 1 hour in bath, un-mordanted wool 1 hour in bath. The mordanted wool is slightly more yellow than the sample with mordant.

I have not yet completed lightfastness tests on any of these samples but they are in process. I would guess that the deeper, tannin-rich colors will be more lightfast than the brighter flavonols.

It’s time to collect black walnuts! The black walnut tree (Juglans nigra) is native to eastern North America. The outer husk of the nut is the source of dye. The colorant is juglone. It is a direct dye, which means that no mordant is necessary when used with a protein fiber. There are some tannins in the husk but that is very secondary to the strong juglone. I have not found a better dye to achieve a rich, fast, brown on protein fibers. Cellulose may be dyed as well, but that requires a mordant.

The best time to gather the nuts is when they are still green: newly fallen or ready to fall off the tree. If the nuts rot and turn black on the ground the dye will be damaged. I preserve the fresh nuts in the freezer for year round dyeing.

I have experimented with drying the nuts carefully on racks to prevent rotting. When I compared these dried nuts to fresh/frozen walnuts in the dyebath it was clear that they contain far less dye. On the other hand, drying may be a practical solution.

Dry walnut vs. fresh: one walnut per 20 grams of fiber.Increasing the number of dry walnuts deepens the color

Walnut has been cooked long enough to split open the exocarp or outer skin

Fresh and dried walnuts and the actual “nut” inside the fruit

I have learned that the secret to dyeing with black walnut is slow dyeing and lots of patience. I put the entire nut(s) in a mesh bag (fresh or dry), cover with water and simmer until the outer skin (the exocarp) breaks open, releasing the soft husk underneath which contains the dye. Then I cool the bath a bit, add the fiber, leaving the entire nut in the bath (in the mesh bag) during the entire dyeing process. The mesh keeps the fiber clean. I heat the dyebath slowly and leave it for a long time. There were many occasions that I was disappointed in walnut dye, only to finally learn that it takes TIME. I still have to resist the temptation to add more walnut to the bath during the first hour of dyeing, remembering that the dye will get darker with a longer bath.

One fresh walnut was used for 20 grams of fiber. Note the effect of time in the dye bath. Heat was turned off after 4 hours and the fiber remained in the dyebath overnight

1 dry walnut per 20 grams fiber

My typical approach to dyeing with walnuts is to grab a handful of them, making a good “guess” as to how many I need. I decided to approach the dyeing more scientifically in order to control the color and know how many walnuts were actually required to obtain the color I wanted.

A fresh walnut weighs about 90 grams. A dry walnut weighs about 30 grams. The dry nut contains a lot less water and now I know that it also contains a lot less dye.

The nut inside the husk (this is the not the dye) = approx. 20 g

A fresh nut contains approx. 70 g of walnut dye material

A dry nut contains approx. 10 g of walnut dye material.

I now calculate about one fresh/frozen nut per 20 grams of fiber (or about 350% w.o.f.). If I am using dry walnuts I will double that amount, at least. Many more dry walnuts will be required to achieve the same color as the fresh walnuts.

Black walnuts are a most versatile dye. The presence of tannin means that the color can be dulled and deepened with an afterbath of ferrous but when dyed over a deep indigo, a near black color can be achieved on wool or silk without the use of any mordant.